The OSVR plugin has been updated to work with each engine version through 4.9. As the description says in each branch though the plugin is in its preliminary state so there is support but it might be a bit buggy. When you’re on the plugin’s GitHub master branch page make sure to click the ‘branch’ button as the screenshot shows and select the correct engine version (4.6-4.9 is available).
Plugin’s Main Github Page (master branch): GitHub - OSVR/OSVR-Unreal: OSVR plugin for Unreal Engine
4.8 Plugin Update (4.8 branch): GitHub - OSVR/OSVR-Unreal at ue4_8
4.9 Plugin Update (4.9 branch): GitHub - OSVR/OSVR-Unreal at ue4_9
For modifying and creating your own plugins definitely check out these UE4 Documentation links:
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